1. Field of the Invention
The present invention relates to a scanning acoustic tomograph, and more specifically, to a scanning acoustic tomograph which measures the internal part of a subject in a non-destructive manner using ultrasonic waves in water as an ultrasonic transmission medium, and displays an exploration video and the like of the subject or determines the acceptance of an internal defect.
2. Background Art
Scanning acoustic tomographs perform scanning by repeatedly performing the irradiation of ultrasonic waves toward a subject and the reception of the ultrasonic waves reflected or transmitted from the subject to express the intensities of the received ultrasonic waves as an image. Using properties in which the intensities of the ultrasonic waves reflected or transmitted from the subject are different from each other due to acoustic impedance of the respective parts of the subject, the scanning acoustic tomographs can examine the internal state of the subject in a non-destructive manner.
Since ultrasonic waves have such properties as to be difficult to transfer to a gas, scanning acoustic tomographs generally use water as an ultrasonic transmission medium to soak a subject and an ultrasonic transducer in the water to thus perform the examination.
As background art of this technical field, there is JP-A-2002-296247. JP-A-2002-296247 discloses that “the metal band is inserted between the ultrasonic transmitting element and the ultrasonic receiving element disposed opposed to each other in a water tank, and an ultrasonic beam is transmitted and received between the ultrasonic transmitting element and the ultrasonic receiving element via the metal band to detect an internal defect of the metal band” (see the abstract).